Inhibition of inducible nitric oxide production and iNOS protein expression in lipopolysaccharide-stimulated rat aorta and Raw 264.7 macrophages by ethanol extract of a Chinese herbal medicine formula (RCM-101) for allergic rhinitis

George Binh Lenon, Chung Guang Li, Charlie Changli Xue, Francis Chung Kong Thien, David Frederick Story

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    17 Citations (Scopus)

    Abstract

    Aim of the study: A Chinese herbal formula (RCM-101) has shown to be effective in reducing symptoms of seasonal allergic rhinitis (SAR) in a randomised, placebo-controlled clinical trial. The aim of this study is to investigate the effects of RCM-101 on the actions and synthesis of nitric oxide (NO). l-Arginine-induced endothelium-independent relaxations were studied in rat isolated aorta which was pre-treated with lipopolysaccharide (LPS). Materials and methods: NO production and inducible nitric oxide synthase (iNOS) protein expression were studied in LPS and interferon γ-stimulated murine macrophages (Raw 264.7), measured by NO sensors and Western blotting. Results: In rat aortic preparations, RCM-101 significantly inhibited endothelium-independent relaxations to l-arginine, but not affected those to sodium nitroprusside (SNP). In Raw 264.7 cells, RCM-101 and some of its individual ingredients (e.g., Radix glycyrrhizae, Radix bupleuri, Radix saposhnikoviae and Atractylodis rhizome macrocephalae) significantly inhibited the NO production and iNOS protein expression. Conclusions: The findings indicate that RCM-101 may inhibit inducible NO production by suppressing iNOS. In addition, its inhibitory action of iNOS is likely to be mediated by several key herbal ingredients.
    Original languageEnglish
    Pages (from-to)547-553
    Number of pages7
    JournalJournal of Ethnopharmacology
    Volume116
    Issue number3
    DOIs
    Publication statusPublished - 2008

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